Noyes-Whitney Equation:

Noyes-Whitney Equation:

Noyes & Whitney described the quantitative analysis of the amount of drug dissolved from a solid particle as a function of time.

Derivation from Fick’s law of diffusion:

                 

Equation:

                                    D_c /S

                   dc/dt=                  (C_s – C)

                                      h

Where,

c = amount of drug dissolved (mg) in time t(s).

D_c = diffusion coefficient of the drug (cm²s^-1).

S = surface area of drug (cm²)

h = thickness of the diffusion layer liquid film (cm).

C_s = Saturation solubility of the drug (mg.cm^-3).

C = concentration of drug in bulk solution (mg.cm^-3).